In recent years, concerns about the occurrence and fate of active pharmaceutical ingredients, solvents, intermediates and raw materials that could be present in pharmaceutical industry effluents has gained increasing attention. Conventional treatment methods, such as activated sludge, are not sufficient enough to remove active pharmaceutical ingredients completely. As a result, complementary treatment methods like coagulation and flocculation are often used and play a critical role in industrial and municipal wastewater treatment. The primary goal of these methods is to destabilize and remove colloidal particles along with other organic/inorganic contaminants. Recently empirical works have considered ozone as the most promising oxidant for the removal of micro-pollutants. The current study examined the effectiveness of coagulation/flocculation process using ferric chloride, poly-aluminum chloride, and aluminum sulfate as a reasonable approach to tackle the issue of treating pharmaceutical wastewater. In addition, the results were compared with the process using only ferric chloride that was the coagulant of an actual treatment plant. Then, improvement of the process performance was investigated using ozone as an oxidant. In conclusion, it was found out that poly-aluminum chloride presented better performance among two other coagulants and also adding 200 mg/L of poly-aluminum chloride can lead to 97-98% turbidity removal efficiency. Moreover, poly-aluminum chloride was capable of reducing most of the environmental parameters such as chemical oxygen demand and total dissolved solid with the removal efficiency of 70% and 68%, respectively. Additionally, ozonation improved the coagulation process, especially iron ion removal, and dramatically decreased the concentration from 5.68 to 0.19 mg/L.

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